Pump



Patented Oct. 15, 1935 PATENT OFFICE PUMP Michael D. Aisenstein, Berkeley, Calif., assignor to United Iron Works, Oakland, Calif., a corporation of California Application February 6, 1933, Serial No. 655,461 2 Claims. (Cl. 103-108) The invention relates to pumps, and particularly to pumps such as the multi-stage centrifugal type where an auxiliary casing or housing is enclosed about the pump casing in which the impellers are contained, the outer or extra casing serving as a protective and reenforcing covering for the inner casing which in pumps of this class, and particularly when used for hot oils and the like, are subject to considerable axial expansion and contraction, especially during the starting and stopping operations. This movement of the inner casing takes place without an accompanying movement of the outer casing, and since it would be relatively expensive and therefore commercially impractical to provide separate sealing connections .at the juncture of each of the intercommunicating passagesthat is the inlet and delivery-between the casings, usually no attempt is made to prevent leakage thereat and go the fluid is allowed to escape into the space between the casings, the discommunication of the inlet and delivery fluids being effected by the use of a sealing joint located in said space somewhere between the inlet and outlet passages.

Heretofore, however, even the one seal has been difiicult of effective accomplishment owing to the axial movement especially longitudinal movement of the one casing relative to the other, and while various attempts to provide an adequate seal had been made, in general they were unsuccessful owing principally to the fact that a proper seal was secured only while the pump was operating at full speed .and continuously. In most of the pumps heretofore designed, the retention of the seal over a period of use depended practically entirely on the inherent expansibility of compressible gaskets, so that not only was considerable force required to be exerted by such gaskets, but the necessity of frequent replacement of the gaskets made necessary the frequent dismantling and interruption of the operation of the pump.

In accordance, however, with my invention, instead of designing the pump whereby on expansion and contraction of the inner casing the sealing parts may come together or move apart, I construct the pump whereby said sealing parts are rigidly held together at all times and the connection therebetween forms the only rigid connection between the casings. In this way axial or longitudinal expansion or contraction of the inner casing may take place without resistance at each side of the sealing joint and consequently with practically no effect on the joint itself. Thus, whether the pump is starting, running, or stopping, or whether the fluid operated upon by the pump is hot, cold or otherwise, the seal between the chambers will be effectively maintained, and at the same time since the inner casing is free to expand or contract at will, no strains due to unequal expansion will be transmitted 5 from the inner to the outer casing.

Another feature of my invention is that the tightness of the sealing joint or connection between the chambers may be adjusted or regulated from the exterior of the pump and without re- 0 quiring any interruption in the operation of the pump.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following descrip- 5 tion of the preferred form of the invention which is illustrated in the drawing accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by said drawing and description may be 20 adopted within the scope of the invention as set forth in the claims.

Referring to said drawing:

Figure 1 is a longitudinal sectional view through a pump embodying the features of my invention. 25

Figure 2 is a transverse sectional view of the pump taken on the line 2-2 of Figure 1.

The features of my invention are embodied, as here shown, in a pump 2 of the multi-stage centrifugal type, and designed for use especially 30 for hot oil. In the design illustrated the pump includes an outer casing. 3 which encloses an inner casing 4 in which are contained a series of impellers 6. Between the casings is left an annular space I which preferably extends for 35 the full length of the pump.

The impellers 6 are fixedly mounted on a common shaft 8 which is journalled in bearings 9' and it provided in opposite end walls 9 and it] of the outer casing. The inner casing 4 is mount-- 40 ed, adjacent the suction end of the pump, on a sleeve ll on the shaft, and adjacent the discharge end is mounted on a cylindrical extension 12 of the'outer casing end plate 10. The inner casing is permitted to slide axially or lon- 5 gitudinally freely on the sleeve andv extension, but is held at seal I9 against both rotational and longitudinal displacement by means of bolts l3 whichsecure the two casings together as will be more fully hereinafter described. 50

In the outer casing 3 are provided inlet and outlet openings l4 and I5 whichcommunicate with the suction and delivery chambers 16 and l1 respectively in the inner casing; the associated openings and chambers providingfor the. incom- 5 ing and outgoing fluid, separate passages which extend through the space 1. Since in the operation of the pump, the inner casing is subject to considerable expansion and contraction and therefore caused to move axially or longitudinally on each side of the seal l9 within and relative to the outer casing. The use of an individually sealed joint between each of the associated openings and chambers While possible of accomplishment, would be comparatively expensive, and therefore not practical from a commercial standpoint. It is not only feasible but highly desirable, therefore in pumps of this type, to omit the individual sealing joints and to use in place thereof a means of sealing one portion of the space i from the other so that entry of the incoming or outgoing liquid into the space I is not resisted, but the communication of one liquid space with the other should be prevented. To afford, then, a proper seal between one of the liquid passages and the portion of the space communicating with the other of the passages, notwithstanding the essential requirement of permitting free axial or longitudinal expansion and contraction of the inner unit, that is the inner casing and impeller assembly, relative to the outer housing, is as aforesaid one of the main purposes of the present invention.

In the present embodiment of the invention the seal or joint in the space 1 is located in close proximity to the inlet, and as will be clear from Figure 1, utilizes as a part of the joint, as likewise do most other pumps of this class, opposing annular shoulders or faces I8 and 19 provided on the outer and inner casings respectively, the effectiveness of the seal depending on the retention of the faces in such cooperative relation that no liquid may pass therebetween. In previous designs of pumps, retention of the faces together was made dependent on some variable factor, such .as the differential in the pressures of the different chambers, or an expansible element resisting the separation of the casings at the face portions. In my pump, as previously explained, the faces I8 and I9 are arranged to be held together rigidly, and to'this end the outer and inner casings are directly secured together for effecting such connection. As here shown, connection between the casings is effected through means of bolts l3 as previously explained, and the latter, as will be clear from Figure 1, are threaded in the inner casing and engaged in nuts 2| which bear against the outer side of the casing wall 9. The bolts extend parallel to the longitudinal axis of the pump shaft so that the faces may be readily drawn together as tightly as desired.

In the embodiment of the invention as disclosed in Fig. 1 it is noted that the major portion of the bolts I3 are exposed in a space 1 and therefore to the contents of said space 1. The exposure of the bolts I3 is not only desirable but is important, since a sudden change of temperature caused by a quick change of liquid contents at widely different temperatures will result properly and timely to expand the bolts even though they may be ordinary ones and thereby relieve them of excessive strains during sudden temperature changes of the liquid contents of space I as pointed out. Of course, it is contemplated as being within the purview of this invention to substitute any other feasible means to produce the fixed, permanent or constant seal at l9 to prevent leakage from one portion of space or chamber Ito another portion thereof.

In this connection attention is called to the fact that the fixed joint or seal at IE! not only prevents leakage and resulting ineificiency, but it prevents rotation or angular displacement of the inner casing 4 with reference to the outer 5 casing 3, The prevention of angular displacement, as above pointed out is very important, since it must effectively overcome the torque produced by the rotating shaft and impellers. Its presence spells efficiency and success, while its absence spells inefiiciency, failure and destruction.

It will now be evident that with a fixed sealing connection as above described, it is practically immaterial in respect to the effectiveness thereof, whether the pump is running, or is being started or stopped, and since said connection as a whole is the only one between the casings which affects the relative axial or longitudinal displacement of the inner unit relative to the outer casing, the longitudinal expansion and contraction of the inner unit and the accompanying longitudinal slipping of the end portion thereof on the guide extension l2 will be virtually unrestricted and may take place without any resistance on the part of the connection. It may be noted that due to the comparative shortness of the portion of the inner casing between the sealing joint .and the end adjacent the outer casing wall 9 there would be little if any appreciable longitudinal expansion and contraction; however, should there so be, the casing is free to slide over the unthreaded portion of the bolts [3, the latter being preferably formed of a material having a relatively low coeflicient 85 of expansion and contraction so that the rigidity of the sealing connection will remain substantially the same in spite of any contraction of the inner casing portion aforesaid.

A rather important feature of the invention 4,0 is the accessibility for adjustment of the degree of tightness of the sealing joint. In this connection it will be seen that the nuts 2| are exposed for turning from the exterior of the casing, thus permitting adjustment of the joint without requiring any dismantling of the pump or, as a matter of fact, without interfering with its operation.

I claim:

1. A centrifugal multi-stage pump having an outer casing and an inner casing, said casings having cooperating inlet and outlet openings, longitudinal means on contiguous ends of each casing and arranged in telescopic relation, whereby the inner casing is centered within the outer casing and said inner casing is mounted for longitudinal, freely slidable engagement at one end with'said outer casing to compensate for differences in expansion and contracting relatively of said casings, said casings having cooperating shoulders or flanges in spaced .relationfrom their opposite ends but adjacent the inlet end of the pump, said shoulders or flanges being arranged to provide centering means for the inner casing in said outer casing and to form a single seal between the inlet and outlet openings of said inner casing, means comprising bolts located at the inlet end of the pump to draw said shoulders or flanges together and positively prevent relative angular displacement of said casings, said '0 outlet openings being in direct communication with each other and with the space between said casings, thereby substantially equalizing both the temperature and pressure on the major portions of said casings, said bolts, for drawing the 15 shoulders or flanges together, having their major portions exposed to a liquid receiving space of said pump, whereby said bolts may respond to the temperature of the contained liquid even though liquids at widely different temperatures are suddenly changed, thereby relieving said bolts and parts connected thereby from undue strains resulting from sudden wide differences in temperature.

2. In a pump construction designed to respond to sudden temperature changes, the substructure including an outer casing section having inlet and outlet openings and a liquid receiving space in combination with an inner casing having both an inlet and an outlet, cooperating shoulder or flanges on said outer casing section and on said inner casing adjacent said inlet, whereby said inner casing may be properly centered in said section, means located at the inlet end of the pump to positively engage said outer casing section and inner casing respectively and draw said shoulders or flanges together and form a single constant seal between said section and inner casing and for preventing relative angular displacement of said section and inner casing and comprising bolts engaging both the section and inner casing, said bolts having their major portions exposed in the liquid receiving space of said section whereby said bolts may respond favorably to sudden temperature changes in the liquid contents of said space, to relieve undue strains on said bolts and the parts con- 15 nected thereby.

MICHAEL D. AISENS'I'EIN. 

